New types of memory have demonstrated significant potential to compete with commonly utilized forms of memory. For example, non-volatile spin-transfer torque random access memory (referred to herein as ST-RAM) has been discussed as a “universal” memory. Magnetic tunnel junction cells have has attracted much attention for their application in ST-RAM due to their high speed, relatively high density and low power consumption.
Most activities have been focused on magnetic tunnel junction cells with in-plane magnetic anisotropies. However, there are limits on how low the switching current can be for adequate thermal stability, which further limits the size of the CMOS transistor which ultimately limits the density of the memory array. In addition, there is very low tolerance of the cell shape and edge roughness, which can be challenging photolithographic techniques. Techniques, designs and modifications designed to improve magnetic tunnel junction cell structures and materials remain an important area of advancement to maximize the advantages of ST-RAM.